Microsoft Patches For USB Key Vulnerability

Driver bug would allow anyone with physical access to compromise a PC by using exploit code loaded onto a USB storage device.

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Microsoft on Tuesday patched a number of vulnerabilities affecting its Windows and Mac OS X products, including one Windows bug that could be exploited by attackers to take control of a PC via a USB key.

All told, Microsoft released seven security bulletins, including four "critical" warnings -- referring to bugs that can be used to remotely compromise a PC -- involving Internet Explorer, Silverlight, Visio Viewer 2010 and SharePoint.

Security experts' consensus is to first patch IE -- all versions of the browser, from IE6 to IE10, are at risk -- because some of the eight fixed bugs could be exploited via drive-by attacks launched from compromised websites.

Microsoft also released three "important" security bulletins, including fixes for bugs in Microsoft OneNote, Outlook for Mac and Windows kernel-mode drivers. The last vulnerability affects Windows XP, Vista, 7 and 8; the 2003, 2008, 2008 R2 and 2012 versions of Windows Server; and multiple versions of Server Core installations.

The kernel-mode driver vulnerabilities also enable this scary security scenario: "An attacker could own your machine by inserting a malicious USB device," said Dustin Childs, group manager for response communications for Microsoft Trustworthy Computing, in a blog post.

The issue isn't that malware can be installed on a USB-compatible storage device, but rather that by exploiting the USB driver vulnerability, an attacker wouldn't have to authenticate to a targeted PC. "While this isn't the first issue to leverage physical access and USB devices, it is different in that it doesn't require a machine to be logged on," said Childs. "It also provides kernel-level code execution where previous attacks only allowed code execution at the logged-on level. Because of this, someone with casual physical access, such as a custodian sweeping your office at night or a security guard making his rounds, could simply plug in a USB device to perform any action as an administrator."

Beyond installing the IE patches, said Childs, "this is also a good reminder for companies to include physical security in their threat modeling."

Until a business can install the patch, Andrew Storms, director of security operations at nCircle, offered a short-term fix. "The good news is you don't need to put glue in your USB ports to protect yourself," he said via email. "Either install the patch ASAP, or deploy a GPO policy to temporarily disable USB ports until the patch is completely deployed."

Microsoft also announced Tuesday that it's decided to not use its monthly "Patch Tuesday" approach for distributing Windows Store app security fixes. "We will deliver high quality security updates for Windows Store apps as they become available," said Mike Reavey, a Microsoft Trustworthy Computing senior director, in a blog post. "This applies to Microsoft apps that are installed using the Windows Store and to apps like Mail, which are preinstalled with Windows 8 but updated using the Windows Store. Providing security updates to these apps more frequently will allow us to add new functionality, fix issues and improve security. This will also help developers to avoid introducing new issues during the update process."

Reavey said that users will be able to install any updates in devices by clicking on the store tile in Windows 8, then selecting available updates. He also said Microsoft would document all fixes made, in accompanying security bulletins.

Adobe, as part of its quarterly patch release cycle, Tuesday also released security updates for Adobe Flash Player running on Windows, Mac OS X, Linux and all versions of Android.

"These updates address vulnerabilities that could cause a crash and potentially allow an attacker to take control of the affected system," said Adobe's related security bulletin. The updates patch four bugs -- an integer overflow vulnerability, use-after-free vulnerability, memory corruption vulnerability, and heap buffer overflow vulnerability -- that could be exploited by an attacker to execute arbitrary code. Adobe said the risk of the vulnerability being exploited is highest for Windows systems, followed by Mac OS X, and then the Linux and Android systems.

Obviously, it's been a busy month for patching, bolstered by Mozilla and Google, which last week released patched versions of Firefox and Chrome less than 24 hours after security researchers at the Pwn2Own competition at the CanSecWest security conference demonstrated new zero-day vulnerabilities against both browsers. Although researchers also successfully exploited zero-day bugs in Adobe Flash and Reader, as well as Internet Explorer, Adobe and Microsoft have yet to release fixes for those exploits. Multiple security experts said they expect both vendors to issue related patches by next month.

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Published: 2015-03-31The build_index_from_tree function in index.py in Dulwich before 0.9.9 allows remote attackers to execute arbitrary code via a commit with a directory path starting with .git/, which is not properly handled when checking out a working tree.